Electric scissors

ABSTRACT

Electric scissors ( 1 A,  1 B) is provided with: a first blade ( 2 A,  2 B); a second blade ( 3 A,  3 B); a toggle link mechanism ( 7 A,  7 B) including a first link ( 71 A,  71 B), a second link ( 72 A,  72 B), and a drive shaft ( 70 A,  70 B); and a drive section ( 5, 6 ). One end of the first link ( 71 A,  71 B) is rotatably connected to a transmission portion ( 21 A,  21 B) of the first blade ( 2 A,  2 B). One end of the second link ( 72 A,  72 B) is rotatably connected to a transmission portion ( 31 A,  31 B) of the second blade ( 3 A,  3 B). The other end of the first link ( 71 A,  71 B) is rotatably connected to the other end of the second link ( 72 A,  72 B) through the drive shaft ( 70 A,  70 B). The drive section ( 5, 6 ) is configured to open/close the first blade ( 2 A,  2 B) and the second blade ( 3 A,  3 B) by displacing the drive shaft ( 70 A,  70 B) in a direction perpendicular to an axial direction of the drive shaft ( 70 A,  70 B).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electric scissors, used to prunebranches of trees or the like, for cutting objects to be cut, such asthe branches, by opening and closing the blades using a drive power of amotor.

2. Background Art

Conventionally, branches or the like have been pruned with scissors byopening/closing blades of scissors with a hand of the user. However, forthe purpose of saving labor of this work, electric scissors are proposedthat can cut objects to be cut, such as the branches, by opening/closingthe blades using a drive power of a motor.

Such electric scissors include a fixed blade and a movable blade beingrotatable around a shaft serving as a fulcrum. A configuration referredto as a link type and a configuration referred to as a gear type areknown as the configurations of systems for driving the movable blade.

Link-type electric scissors are configured so that the movable bladethereof is formed into an L-shape, for example, having a cutting edgeportion on one side of the movable blade with respect to the shaft onwhich the movable blade is supported and having an arm portion on theother side of the movable blade. Furthermore, the electric scissors havea ball screw for converting a rotation of a motor into a linear motionof a nut portion and a link for connecting the nut portion to the armportion of the movable blade. With this configuration, the linearmovement of the nut portion is transmitted to the arm portion of themovable blade via the link, and the movable blade is rotated around theshaft serving as a fulcrum (for example, refer to Patent Document 1).

Patent Document 1: U.S. Pat. No. 5,002,135

Gear-type electric scissors are configured so that the movable bladethereof has an arc-shaped gear disposed coaxially with a shaft on whichthe movable blade is supported and so that the rotation of a motor istransmitted to the movable blade using a mechanism in which a bevel gearand a spur gear or the like are combined (for example, refer to PatentDocument 2).

Patent Document 2: JP-A-11-128561

The link-type electric scissors are characterized in that as the bladesare closed, the cutting torque thereof becomes low. Generally speaking,in the case of cutting an object to be cut with scissors, a large torqueis not required at the beginning of the closing of the blades. However,a large torque is required as the blades are closed.

For this reason, for the purpose of obtaining a desired torque when theblades are closed, the link-type electric scissors are configured sothat a large torque can be generated using a motor having a largeoutput, for example. With this configuration, the large torque isapplied at the beginning of the closing of the blades.

Hence, a load applied to the drive system, such as the ball screwmechanism, becomes large, and the durability of the drive system isdegraded. On the other hand, for the purpose of improving thedurability, the drive system is required to be constructed sturdily soas to cope with the large load. Consequently, although the electricscissors are used as a tool held in the hand, it is difficult to makethe electric scissors light in weight, and the apparatus eventuallybecomes large in size and the operability thereof is degraded.

In the gear-type electric scissors, a constant torque is obtainedregardless of the opening degree of the blades. However, the gearsthereof are required to be increased in thickness to withstand the largeload. It is thus difficult to make the electric scissors light inweight, and the apparatus eventually becomes large in size. On the otherhand, if the gears are decreased in thickness to make the apparatuscompact in size and light in weight, the durability thereof is degraded.

SUMMARY OF THE INVENTION

One or more embodiments of the invention provide electric scissorscapable of obtaining a torque required for cutting an object to be cutwithout increasing a weight thereof.

In accordance with one or more embodiments of the invention, electricscissors (1A, 1B) are provided with: a first blade (2A, 2B) including acutting edge portion (20A, 20B) and a transmission portion (21A, 21B),and rotatably supported by a shaft (4A, 4B) serving as a fulcrum; asecond blade (3A, 3B) including a cutting edge portion (30A, 30B) and atransmission portion (31A, 31B), wherein an object between the firstblade (2A, 2B) and the second blade (3A, 3B) is cut by closing the firstblade (2A, 2B) and the second blade (3A, 3B); a toggle link mechanism(7A, 7B) including a first link (71A, 71B), a second link (72A, 72B),and a drive shaft (70A, 70B); and a drive section (5, 6). One end of thefirst link (71A, 71B) is rotatably connected to said transmissionportion (21A, 21B) of the first blade (2A, 2B). One end of the secondlink (72A, 72B) is rotatably connected to said transmission portion(31A, 31B) of the second blade (3A, 3B). The other end of the first link(71A, 71B) is rotatably connected to the other end of the second link(72A, 72B) through the drive shaft (70A, 70B). The drive section (5, 6)is configured: to close the first blade (2A, 2B) and the second blade(3A, 3B) by displacing said drive shaft (70A, 70B) in a direction ofincreasing an angle between the first link (71A, 71B) and the secondlink (72A, 72B); and to open the first blade (2A, 2B) and the secondblade (3A, 3B) by displacing said drive shaft (70A, 70B) in a directionof decreasing said angle between the first link (71A, 71B) and thesecond link (72A, 72B).

According to the electric scissors having the above structure, when thedrive shaft is displaced in the direction of increasing the angle formedby the first link and the second link of the toggle link mechanism, theconnection of the first link and the second link being bent at the driveshaft serving as a fulcrum, the first blade and the second blade areclosed while being rotated around the shaft serving as a fulcrum. As theangle formed by the first link and the second link of the toggle linkmechanism is increased and the first blade and the second blade areclosed, a generated cutting force increases. As a result, a largecutting torque can be generated in the latter half of the closingoperation of the first blade and the second blade.

According to the electric scissors having the above structure, since alarge cutting torque can be generated in the latter half of the closingoperation of the blades requiring a large torque to cut an object to becut, such as a branch, the torque required to cut the object to be cutcan be obtained without increasing the weight of the mechanisms of theelectric scissors.

Hence, a load applied to the drive system of the electric scissors canbe reduced, and the drive system can be made compact in size and lightin weight without degrading durability. Since the drive system can bemade compact in size and light in weight, the entire apparatus can alsobe made compact in size and light in weight. Consequently, theoperability of the tool that is held in the hand and used can beimproved.

Further, the second blade (3A) may be rotatably supported by said shaft(4A) serving as a fulcrum.

Said angle between the first link (71A, 71B) and the second link (72A,72B) may become close to 180°, when the first blade (2A, 2B) and thesecond blade (3A, 3B) are closed to a maximum extent.

Moreover, the drive section may include a motor (5) to be rotatablydriven, and a ball screw mechanism (6) configured to convert a rotationof the motor (5) into a linear motion and to transmit the linear motionto said drive shaft (70A, 70B) of said toggle link mechanism (7A, 7B).

Other aspects and advantages of the invention will be apparent from thefollowing description, the drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view showing a configuration example ofelectric scissors according to a first exemplary embodiment.

FIG. 2 is a side sectional view showing a configuration example of theelectric scissors according to the first exemplary embodiment.

FIG. 3 is a graph showing a relationship between a generated torque anda torque required for cutting.

FIG. 4 is a side sectional view showing a configuration example ofelectric scissors according to a second exemplary embodiment.

FIG. 5 is a side sectional view showing a configuration example of theelectric scissors according to the second exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments of electric scissors of the present invention willbe described below referring to the accompanying drawings.

A Configuration Example of Electric Scissors According to a FirstExemplary Embodiment

FIGS. 1 and 2 are side sectional views showing a configuration exampleof electric scissors according to a first exemplary embodiment. FIG. 1shows a state in which the blades thereof are opened, and FIG. 2 shows astate in which the blades are closed.

In electric scissors 1A according to the first exemplary embodiment, afirst movable blade 2A and a second movable blade 3A are rotatablysupported by a shaft 4A serving as a fulcrum.

In the electric scissors 1A, the rotation of a motor 5 is converted intoa linear motion using a ball screw mechanism 6, and the drive power ofthe motor 5, the rotation of which is converted into a linear motion, istransmitted to the first movable blade 2A and the second movable blade3A using a toggle link mechanism 7A. As a result, the first movableblade 2A and the second movable blade 3A are rotated around the shaft 4Aserving as a fulcrum, thereby being opened/closed.

In the electric scissors 1A, the shaft 4A is supported on a frame 8A,and the movements of the ball screw mechanism 6 and the toggle linkmechanism 7A are guided along the frame 8A. Furthermore, in the electricscissors 1A, the above-mentioned respective components are installed ina housing 9, and the user can perform operation while holding thehousing 9.

The respective components will be described below in detail. The firstmovable blade 2A, an example of a first blade, is equipped with acutting edge portion 20A disposed on one side of the first movable blade2A with respect to a position in which the first movable blade 2A issupported by the shaft 4A and is also equipped with a blade arm 21Adisposed on the other side of the first movable blade 2A with respect tothe position and serving as a transmission portion, the angle formed bythe cutting edge portion 20A and the blade arm 21A being a predeterminedobtuse angle. The cutting edge portion 20A and the blade arm 21A of thefirst movable blade 2A may be integrated into one component. However, itis preferable that the cutting edge portion 20A and the blade arm 21Ashould be independent components so that the cutting edge portion 20Acan be replaced easily.

The second movable blade 3A, an example of a second blade, is equippedwith a cutting edge portion 30A disposed on one side of the secondmovable blade 3A with respect to a position in which the second movableblade 3A is supported by the shaft 4A and is also equipped with a bladearm 31A disposed on the other side of the second movable blade 3A withrespect to the position and serving as a transmission portion, the angleformed by the cutting edge portion 30A and the blade arm 31A being apredetermined obtuse angle. As in the case of the first movable blade2A, the cutting edge portion 30A and the blade arm 31A of the secondmovable blade 3A may be integrated into one component. However, it ispreferable that the cutting edge portion 30A and the blade arm 31Ashould be independent components so that the cutting edge portion 30Acan be replaced easily.

The shaft 4A is installed in the frame 8A using a mounting fixture 40Awhile the cutting edge portion 20A of the first movable blade 2A and thecutting edge portion 30A of the second movable blade 3A are exposed fromthe housing 9. The first movable blade 2A and the second movable blade3A are configured so that the cutting edge portions 20A and 30A can bereplaced by attaching and detaching the mounting fixture 40A to and fromthe shaft 4A.

The motor 5 and the ball screw mechanism 6 constitute an example of adrive section, and the drive shaft of the motor 5 is connected to aspeed reducer 50 having planet gears, for example. The ball screwmechanism 6 is equipped with a screw shaft 60 connected to the outputshaft of the speed reducer 50 and a nut portion 61 in which balls, notshown, inserted in the screw groove of the screw shaft 60 are built in.

In the ball screw mechanism 6, a guide shaft 62 provided in the nutportion 61 is inserted into a guide groove 80 that is provided in theframe 8A in a direction in parallel with the screw shaft 60. When thescrew shaft 60 of the ball screw mechanism 6 is driven and rotated, therotation of the nut portion 61 around the screw shaft 60 serving as afulcrum is restricted since the guide shaft 62 is guided along the guidegroove 80, whereby the nut portion 61 is moved linearly along the screwshaft 60.

Hence, in the ball screw mechanism 6, the rotation of the motor 5 isconverted into the linear motion of the nut portion 61. As a result, themovement direction of the nut portion 61 is switched depending on therotation direction of the motor 5.

The toggle link mechanism 7A is equipped with a first link 71A and asecond link 72A rotatably connected to each other via a drive shaft 70A.In the toggle link mechanism 7A, one end portion of the first link 71Ais rotatably connected to the blade arm 21A of the first movable blade2A via a shaft 73A serving as a fulcrum. In addition, one end portion ofthe second link, 72A is rotatably connected to the blade arm 31A of thesecond movable blade 3A via a shaft 74A serving as a fulcrum.Furthermore, the other end portion of the first link 71A is rotatablyconnected to the other end portion of the second link 72A via the driveshaft 70A serving as a fulcrum.

In the toggle link mechanism 7A, the connection portion of the blade arm21A of the first movable blade 2A and the first link 71A at the shaft73A is bent, and the connection portion of the blade arm 31A of thesecond movable blade 3A and the second link 72A at the shaft 74A isbent. Furthermore, the connection portion of the first link 71A and thesecond link 72A at the drive shaft 70A is bent.

The drive shaft 70A of the toggle link mechanism 7A is guided along theguide groove 80 of the frame 8A and supported so as to be movable in adirection in parallel with the screw shaft 60. The drive shaft 70A ofthe toggle link mechanism 7A is connected to the nut portion 61 via atransmission member 75 and is moved linearly in conjunction with themovement of the nut portion 61 obtained by the conversion of therotation of the motor 5 into a linear motion using the ball screwmechanism 6.

The first movable blade 2A and the second movable blade 3A are rotatedaround the shaft 4A serving as a fulcrum, thereby being opened/closed.The blades are closed when the blade arm 21A of the first movable blade2A and the blade arm 31A of the second movable blade 3A are rotated indirections in which the angle formed by the blade arm 21A and the bladearm 31A increases.

In the toggle link mechanism 7A, the connection portion of the firstlink 71A and the second link 72A at the drive shaft 70A is bent. Inconjunction with the closing operation of the first movable blade 2A andthe second movable blade 3A, the first link 71A and the second link 72Aare rotated while the drive shaft 70A being moved linearly serves as afulcrum in a direction of increasing the angle formed by the first link71A and the second link 72A. Furthermore, the dimensions and angles ofrespective components are determined so that when the first movableblade 2A and the second movable blade 3A are closed, the angle formed bythe first link 71A and the second link 72A becomes close to 180°. Whenthe angle formed by the first link 71A and the second link 72A becomeslarger than 180°, the first movable blade 2A and the second movableblade 3A are rotated in directions so that they are opened. Hence, thetoggle link mechanism 7A is configured so that the angle formed by thefirst link 71A and the second link 72A does not become larger than 180°.

The electric scissors 1A are equipped with an operation section 10 foropening/closing the first movable blade 2A and the second movable blade3A. The operation section 10 is equipped with an auxiliary trigger 12that operates in conjunction with a first switch 11 for turning on/offthe electric power supplied to the motor 5 and a main trigger 14 thatoperates in conjunction with a second switch 13 for controlling therotation direction, the amount of rotation and the rotation speed of themotor 5.

The auxiliary trigger 12 is installed in the housing 9 so as to berotatable around a shaft 12 a serving as a fulcrum and is equipped witha restricting protrusion 12 b for restricting the operation of the maintrigger 14. The main trigger 14 is installed on the shaft 13 a of thesecond switch 13. When the main trigger 14 is operated and the shaft 13a is rotated, the second switch 13 outputs control signals correspondingto the rotation direction, the amount of rotation and the rotationspeed, whereby the motor 5 is controlled in accordance with the motionof the main trigger 14.

In the electric scissors 1A, when the auxiliary trigger 12 is notoperated and the first switch 11 is in the ON state, the restrictingprotrusion 12 b is locked with the main trigger 14, and the operation ofthe main trigger 14 is restricted.

When the auxiliary trigger 12 is operated so as to be displaced to aposition where the first switch 11 is turned on, the power is turned on,and the restricting protrusion 12 b is released from the main trigger14. As a result, the operation of the main trigger 14 is made possible.Then, when the main trigger 14 is operated while the auxiliary trigger12 has been operated, control signals corresponding to the rotationdirection, the amount of rotation and the rotation speed of the maintrigger 14 are output from the second switch 13, whereby the motor 5 iscontrolled in accordance with the motion of the main trigger 14.

An Example of the Operation of the Electric Scissors According to theFirst Exemplary Embodiment

Next, the operation of the electric scissors 1A according to the firstexemplary embodiment will be described referring to the respectivedrawings. The user holds the housing 9 and operates the auxiliarytrigger 12, thereby displacing the auxiliary trigger 12 to the positionwhere the first switch 11 is turned on. As a result, the power of theelectric scissors 1A is turned on, the restricting protrusion 12 b isreleased from the main trigger 14, and the operation of the main trigger14 is made possible.

The user operates the main trigger 14 while the auxiliary trigger 12 hasbeen operated. In the electric scissors 1A, the control signalscorresponding to the rotation direction, the amount of rotation and therotation speed of the main trigger 14 are output from the second switch13, whereby the motor 5 is controlled in accordance with the motion ofthe main trigger 14.

When the main trigger 14 of the electric scissors 1A is displaced in adirection of being pulled, the motor 5 is controlled so as to be rotatedin a direction of closing the first movable blade 2A and the secondmovable blade 3A. When the main trigger 14 is displaced in a directionof being released, the motor 5 is controlled so as to be rotated in adirection of opening the first movable blade 2A and the second movableblade 3A.

When the motor 5 is driven and rotated in the direction of closing thefirst movable blade 2A and the second movable blade 3A, the nut portion61 is moved linearly in the direction indicated by arrow F1 inaccordance with the rotation direction of the screw shaft 60.

When the motor 5 is driven and rotated in a predetermined direction andthe nut portion 61 is moved linearly in the direction indicated by arrowF1, the drive shaft 70A of the toggle link mechanism 7A connected to thenut portion 61 via the transmission member 75 is moved linearly in thedirection indicated by arrow F1, that is, a direction of approaching theshaft 4A of the first movable blade 2A and the second movable blade 3A.

The displacement of the drive shaft 70A of the toggle link mechanism 7Adue to the linear movement thereof is transmitted to the first movableblade 2A via the first link 71A and also transmitted to the secondmovable blade 3A via the second link 72A.

As shown in FIG. 1, when the drive shaft 70A of the toggle linkmechanism 7A is moved linearly in the direction indicated by arrow F1from a state in which the first movable blade 2A and the second movableblade 3A are opened, the first link 71A and the second link 72A, theconnection portion therebetween being bent at the drive shaft 70A, arerotated in the direction of increasing the angle formed by the firstlink 71A and the second link 72A while the drive shaft 70A being movedlinearly serves as a fulcrum.

The first movable blade 2A having the blade arm 21A connected to thefirst link 71A and the second movable blade 3A having the blade arm 31Aconnected to the second link 72A are rotated around the shaft 4A servingas a fulcrum in a direction of increasing the angle formed by the bladearm 21A and the blade arm 31A. When rotated in the direction ofincreasing the angle formed by the blade arm 21A and the blade arm 31A,the first movable blade 2A and the second movable blade 3A are closed.

Then, when the first movable blade 2A and the second movable blade 3Aare closed, the angle formed by the first link 71A and the second link72A becomes close to 180°. As the first movable blade 2A and the secondmovable blade 3A are closed, the angle formed by the first link 71A andthe second link 72A of the toggle link mechanism 7A becomes close to180°, whereby the first link 71A and the second link 72A approach astate of being aligned along a straight line.

With this configuration, the cutting force generated using the cuttingedge portion 20A of the first movable blade 2A and the cutting edgeportion 30A of the second movable blade 3A is increased in the stateshown in FIG. 2 in which the first movable blade 2A and the secondmovable blade 3A are closed in comparison with the state shown in FIG. 1in which the first movable blade 2A and the second movable blade 3Abegin to be closed.

When the motor 5 is driven and rotated in the direction of opening thefirst movable blade 2A and the second movable blade 3A, the nut portion61 is moved linearly in the direction indicated by arrow F2 inaccordance with the rotation direction of the screw shaft 60.

When the motor 5 is driven and rotated in a direction opposite to thepredetermined direction and the nut portion 61 is moved linearly in thedirection indicated by arrow F2, the drive shaft 70A of the toggle linkmechanism 7A is moved linearly in the direction indicated by arrow F2,that is, a direction of moving away from the shaft 4A of the firstmovable blade 2A and the second movable blade 3A.

As shown in FIG. 2, when the drive shaft 70A of the toggle linkmechanism 7A is moved linearly in the direction indicated by arrow F2from a state in which the first movable blade 2A and the second movableblade 3A are closed, the first link 71A and the second link 72A arerotated in a direction of decreasing the angle formed by the first link71A and the second link 72A while the drive shaft 70A being movedlinearly serves as a fulcrum.

The first movable blade 2A having the blade arm 21A connected to thefirst link 71A and the second movable blade 3A having the blade arm 31Aconnected to the second link 72A are rotated around the shaft 4A servingas a fulcrum in a direction of decreasing the angle formed by the bladearm 21A and the blade arm 31A. When rotated in the direction ofdecreasing the angle formed by the blade arm 21A and the blade arm 31A,the first movable blade 2A and the second movable blade 3A are opened.

FIG. 3 is a graph showing the relationship between a generated torqueand a torque required for cutting. In the electric scissors 1A shown inFIG. 1, etc., the relationship between a torque required for cutting abranch having a certain diameter and supposed to be cut using theelectric scissors 1A and the angle formed by the first movable blade 2Aand the second movable blade 3A is indicated using a solid line. Inaddition, the relationship between the angle formed by the first movableblade 2A and the second movable blade 3A and the generated torque isindicated using a broken line.

In FIG. 3, the vertical axis represents torque, and the horizontal axisrepresents blade angle. Blade angle=0(°) indicates a state in which thefirst movable blade 2A and the second movable blade 3A are opened asshown in FIG. 1, and blade angle A(°) indicates a state in which thefirst movable blade 2A and the second movable blade 3A are closed asshown in FIG. 2. Furthermore, blade angle 1/2A(°) indicates a state inwhich the first movable blade 2A and the second movable blade 3A arehalf opened.

Generally speaking, in the case of cutting a branch having a certaindiameter, no large toque is required when the blades begin to be closed,but a large torque is required in a state in which the blades are closedapproximately three-quarters of the entire blade angle. When it isassumed that the diameters of branches supposed to be cut using electricscissors are up to approximately 20 (mm), a similar tendency is observedregardless of the diameter.

On the other hand, in the case of the electric scissors 1A according tothe first exemplary embodiment equipped with the toggle link mechanism7A, it is found that the generated torque thereof is increased as thefirst movable blade 2A and the second movable blade 3A are closed, incomparison with the torque generated when the first movable blade 2A andthe second movable blade 3A begin to be closed.

For this reason, the electric scissors 1A according to the firstexemplary embodiment equipped with the toggle link mechanism 7A cangenerate a necessary and sufficient torque in the latter half closingoperation of the first movable blade 2A and the second movable blade 3Arequiring a large torque in the case of cutting a branch.

Since the necessary and sufficient torque for cutting a branch can begenerated by using the toggle link mechanism 7A, the output of the motor5 and the output of the ball screw mechanism 6 can be reduced inaccordance with the torque actually required to cut the branch.

More specifically, in the case that the output of the drive section isthe same as that in the conventional apparatus, a cutting forceapproximately two times the maximum load for cutting a branch can beattained by using the toggle link mechanism 7A. For this reason, even ifthe output of the motor 5 or the ball screw mechanism 6 is reduced toapproximately half, it is possible to obtain a force capable of cuttingthe branch.

As a result, the outputs of the motor 5 and the ball screw mechanism 6can be reduced, and the durability of the ball screw mechanism 6, etc.can be improved. In addition, the ball screw mechanism 6, etc. can bemade compact by reducing the outputs of the motor 5 and the ball screwmechanism 6. In the case that the ball screw mechanism 6, etc. can bemade compact in size, the housing 9 being held in the hand of the usercan be designed narrow, and the operability of the apparatus can beimproved. Furthermore, since the outputs of the motor 5 and the ballscrew mechanism 6 can be reduced, the voltage of the battery for drivingthe motor 5 can be lowered. Consequently, the battery can be madecompact in size and light in weight by reducing the number of cells inthe battery, for example.

In the electric scissors 1A according to the first exemplary embodiment,both the first movable blade 2A and the second movable blade 3A aremovable. The rotation angle of the blades when the blades are closedshould only be half the rotation angle obtained in a configuration inwhich one of the blades is a movable blade and the other is a fixedblade, provided that the opening angle of the blades is the same. Hence,in the case that the movement amount of the nut portion per rotation ofthe screw shaft is the same and the output of the ball screw mechanismis also the same in both the single blade drive type and the doubleblade drive type, the stroke of the ball screw mechanism 6 in the doubleblade drive type can be made approximately half the stroke in the singleblade drive type. Hence, the apparatus can be made compact in length.

A Configuration Example of Electric Scissors According to a SecondExemplary Embodiment

FIGS. 4 and 5 are side sectional views showing a configuration exampleof electric scissors according to a second exemplary embodiment; FIG. 4shows a state in which the blades thereof are opened, and FIG. 5 shows astate in which the blades are closed. In FIGS. 4 and 5, mechanisms fordriving one of the blades of the electric scissors are shown, and thehousing, the operation section, etc. thereof are not shown.

Electric scissors 1B according to the second exemplary embodiment have amovable blade 2B and a fixed blade 3B, and the movable blade 2B isrotatably supported by a shaft 4B serving as a fulcrum.

In the electric scissors 1B, the rotation of a motor 5 is converted intoa linear motion using a ball screw mechanism 6, and the drive power ofthe motor 5, the rotation of which is converted into a linear motion, istransmitted to the movable blade 2B using a toggle link mechanism 7B. Asa result, the movable blade 2B is rotated around the shaft 4B serving asa fulcrum, thereby being opened/closed.

The respective components will be described below in detail. The movableblade 2B, an example of a first blade, is equipped with a cutting edgeportion 20B disposed on one side of the movable blade 2B with respect toa position in which the movable blade 2B is supported by the shaft 4Band is also equipped with a blade arm 21A disposed on the other side ofthe movable blade 2B with respect to the position and serving as atransmission portion, the angle formed by the cutting edge portion 20Band the blade arm 21B being a predetermined obtuse angle. The cuttingedge portion 20B and the blade arm 21B of the movable blade 2B may beintegrated into one component or may be independent components.

The fixed blade 3B, an example of a second blade, is equipped with acutting edge portion 30B and a blade arm 31B serving as a transmissionportion. The cutting edge portion 30B and the blade arm 31B of the fixedblade 3B may be integrated into one component or may be independentcomponents.

The drive shaft of the motor 5 is connected to a speed reducer 50 havingplanet gears, for example. The ball screw mechanism 6 is equipped with ascrew shaft 60 connected to the output shaft of the speed reducer 50 anda nut portion 61 in which balls, not shown, inserted in the screw grooveof the screw shaft 60 are built in. When the screw shaft 60 is drivenand rotated, the nut portion 61 is moved linearly along the screw shaft60.

In the ball screw mechanism 6, the rotation of the motor 5 is convertedinto the linear motion of the nut portion 61. As a result, the movementdirection of the nut portion 61 is switched depending on the rotationdirection of the motor 5.

The toggle link mechanism 7B is equipped with a first link 71B and asecond link 72B rotatably connected to each other via a drive shaft 70B.In the toggle link mechanism 7B, one end portion of the first link 71Bis rotatably connected to the blade arm 21B of the movable blade 2B viaa shaft 73B serving as a fulcrum. In addition, one end portion of thesecond link 72B is rotatably connected to the blade arm 31B of the fixedblade 3B via a shaft 74B serving as a fulcrum. Furthermore, the otherend portion of the first link 71B is rotatably connected to the otherend portion of the second link 72B via the drive shaft 70B serving as afulcrum.

The drive shaft 70B of the toggle link mechanism 7B is connected to thenut portion 61 via a transmission member 75 and is moved linearly inconjunction with the movement of the nut portion 61 obtained by theconversion of the rotation of the motor 5 into a linear motion using theball screw mechanism 6.

The movable blade 2B is rotated around the shaft 4B serving as afulcrum, thereby being opened/closed with respect to the fixed blade 3B.The blade is closed when the blade is rotated in a direction in whichthe angle formed by the blade arm 21B of the movable blade 2B and theblade arm 31B of the fixed blade 3B increases.

In the toggle link mechanism 7B, the connection portion of the firstlink 71B and the second link 72B at the drive shaft 70B is bent. Inconjunction with the closing operation of the movable blade 2B, thefirst link 71B and the second link 72B are rotated while the drive shaft70B being moved linearly serves as a fulcrum in a direction ofincreasing the angle formed by the first link 71B and the second link72B. Furthermore, the dimensions and angles of respective components aredetermined so that when the movable blade 2B is closed, the angle formedby the first link 71B and the second link 72B becomes close to 180°.

An Example of the Operation of the Electric Scissors According to theSecond Exemplary Embodiment

Next, the operation of the electric scissors 1B according to the secondexemplary embodiment will be described referring to the respectivedrawings. When the motor 5 is driven and rotated in a direction ofclosing the movable blade 2B, the nut portion 61 is moved linearly inthe direction indicated by arrow F1 in accordance with the rotationdirection of the screw shaft 60.

When the motor 5 is driven and rotated in a predetermined direction andthe nut portion 61 is moved linearly in the direction indicated by arrowF1, the drive shaft 70B of the toggle link mechanism 7B connected to thenut portion 61 via the transmission member 75 is moved linearly in adirection of approaching the shaft 4B of the movable blade 2B. Thedisplacement of the drive shaft 70B of the toggle link mechanism 7B dueto the linear movement thereof is transmitted to the movable blade 2Bvia the first link 71B.

As shown in FIG. 4, when the drive shaft 70B of the toggle linkmechanism 7B is moved linearly from a state in which the movable blade2B is opened, the first link 71B and the second link 72B, the connectionportion therebetween being bent at the drive shaft 70B, are rotated inthe direction of increasing the angle formed by the first link 71B andthe second link 72B while the drive shaft 70B being moved linearlyserves as a fulcrum.

The movable blade 2B having the blade arm 21B connected to the firstlink 71B is rotated around the shaft 4B serving as a fulcrum in adirection of increasing the angle formed by the blade arm 21B and theblade arm 31B. When rotated in the direction of increasing the angleformed by the blade arm 21B and the blade arm 31B, the movable blade 2Bis closed with respect to the fixed blade 3B.

Then, when the movable blade 2B is closed, the angle formed by the firstlink 71B and the second link 72B becomes close to 180°. As the movableblade 2B is closed, the angle formed by the first link 71B and thesecond link 72B of the toggle link mechanism 7B becomes close to 180°,whereby the first link 71B and the second link 72B approach a state ofbeing aligned along a straight line.

With this configuration, the cutting force generated using the cuttingedge portion 20B of the movable blade 2B and the cutting edge portion30B of the fixed blade 3B is increased in the state shown in FIG. 5 inwhich the movable blade 2B is closed in comparison with the state shownin FIG. 4 in which the movable blade 2B begins to be closed.

When the motor 5 is driven and rotated in the direction of opening themovable blade 2B, the nut portion 61 is moved linearly in the directionindicated by arrow F2 in accordance with the rotation direction of thescrew shaft 60.

When the motor 5 is driven and rotated in a direction opposed to thepredetermined direction and the nut portion 61 is moved linearly in thedirection indicated by arrow F2, the drive shaft 70B of the toggle linkmechanism 7B connected to the nut portion 61 via the transmission member75 is moved linearly in a direction of moving away from the shaft 4B ofthe movable blade 2B.

As shown in FIG. 5, when the drive shaft 70B of the toggle linkmechanism 7B is moved linearly from a state in which the movable blade2B is closed, the first link 71B and the second link 72B, the connectionportion therebetween being bent at the drive shaft 70B, are rotated in adirection of decreasing the angle formed by the first link 71B and thesecond link 72B while the drive shaft 70B being moved linearly serves asa fulcrum.

The movable blade 2B having the blade arm 21B connected to the firstlink 71B is rotated around the shaft 4B serving as a fulcrum in adirection of decreasing the angle formed by the blade arm 21B and theblade arm 31B. When rotated in the direction of decreasing the angleformed by the blade arm 21B and the blade arm 31B, the movable blade 2Bis opened with respect to the fixed blade 3B.

While description has been made in connection with specific exemplaryembodiments of the invention, it will be obvious to those skilled in theart that various changes and modification may be made therein withoutdeparting from the present invention.

For example, in the exemplary embodiments referred in the above, themotor 5 and the ball screw mechanism 6 are used as the drive section fordisplacing the drive shaft 70A, 70B in a linear direction perpendicularto an axial direction of the drive shaft 70A, 70B. However, as astructure for converting the rotational motion of the motor 5 to thelinear motion, any well known structures other than the ball screwmechanism 6 can be used. Moreover, an electromagnetic solenoid actuator,a linear motor, or the like can be used as the drive section, instead ofthe combination of the motor 5 and the ball screw mechanism 6.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1A, 1B . . . electric scissors, 2A . . . first movable blade, 2B . . .movable blade, 3A . . . second movable blade, 3B . . . fixed blade, 4A,4B . . . shaft, 5 . . . motor, 6 . . . ball screw mechanism, 7A, 7B . .. toggle link mechanism, 70A, 705 . . . drive shaft, 71A, 71B . . .first link, 72A, 72B . . . second link

1. Electric scissors comprising: a first blade including a cutting edgeportion and a transmission portion, and rotatably supported by a shaftserving as a fulcrum; a second blade including a cutting edge portionand a transmission portion, wherein an object between the first bladeand the second blade is cut by closing the first blade and the secondblade; a toggle link mechanism including a first link, a second link,and a drive shaft; and a drive section, wherein one end of the firstlink is rotatably connected to said transmission portion of the firstblade, one end of the second link is rotatably connected to saidtransmission portion of the second blade, the other end of the firstlink is rotatably connected to the other end of the second link throughthe drive shaft, and the drive section is configured to close the firstblade and the second blade by displacing said drive shaft in a directionof increasing an angle between the first link and the second link, andto open the first blade and the second blade by displacing said driveshaft in a direction of decreasing said angle between the first link andthe second link.
 2. The electric scissors according to claim 1, whereinthe second blade is rotatably supported by said shaft serving as afulcrum.
 3. The electric scissors according to claim 1, wherein saidangle between the first link and the second link becomes close to 180°,when the first blade and the second blade are closed to a maximumextent.
 4. The electric scissors according to claim 1, wherein the drivesection includes a motor to be rotatably driven, and a ball screwmechanism configured to convert a rotation of the motor into a linearmotion and to transmit the linear motion to said drive shaft of saidtoggle link mechanism.